Cerium oxide slurry, cerium oxide polishing slurry and method for polishing substrate using the same

Abstract

The present invention provides a cerium oxide slurry, a cerium oxide polishing slurry, and a method of polishing a substrate by using the same, wherein decrease of scratches and polish at high speed can be realized by reducing the content of coarse grains by improving in the disperse state of cerium oxide particles. The invention relates to a cerium oxide slurry containing cerium oxide particles, dispersant and water, in which the ratio of weight of cerium oxide/weight of dispersant is in a range of 20 to 80 and relates a cerium oxide polishing slurry comprising the cerium oxide slurry and additives such as a water-soluble polymer.

The invention claimed is: 
     
       1. A method of producing a cerium oxide slurry comprising
 oxidizing a cerium compound to obtain a cerium oxide, 
 crushing the cerium oxide to obtain a cerium oxide particles, 
 mixing the cerium oxide particles, a dispersant and water, and dispersing the cerium oxide particles in the water to obtain a cerium oxide disperse solution, 
 microparticulating the cerium oxide particles by sedimentation and sorting the cerium oxide disperse solution to take out only the supernatant from the cerium oxide disperse solution, 
 adjusting the microparticulated cerium oxide disperse solution to prepare the cerium oxide slurry, 
 measuring a ratio of weight of cerium oxide/weight of dispersant in the cerium oxide slurry, and 
 adjusting the concentration of the dispersant in the cerium oxide slurry in order to obtain a ratio that settles in a range of 20 to 40, 
 wherein mean size of particle of the cerium oxide particles in the cerium oxide slurry is 1 to 200 nm, 
 wherein the weight of cerium oxide is the weight of the cerium oxide in the cerium oxide slurry, and 
 wherein the weight of dispersant is the weight of the dispersant in the cerium oxide slurry obtained by measuring a concentration of the dispersant in the cerium oxide slurry after the cerium oxide particles are removed. 
 
     
     
       2. The method of producing a cerium oxide slurry according to  claim 1 , wherein the cerium compound is selected from the group consisting of carbonate, nitrate, sulfate or oxalate of cerium. 
     
     
       3. The method of producing a cerium oxide slurry according to  claim 1 , wherein the dispersant is a compound possessing a solubility in water of 0.1 wt. % to 99.9 wt. %. 
     
     
       4. The method of producing a cerium oxide slurry according to  claim 1 , wherein the dispersant is a salt of poly (meth)acrylic acid. 
     
     
       5. The method of producing a cerium oxide slurry according to  claim 1 , wherein the dispersant is ammonium salt polyacrylate or ammonium salt of copolymer of acrylic acid and methacrylic acid. 
     
     
       6. A method of producing a cerium oxide polishing slurry comprising
 mixing the cerium oxide slurry produced by the method according to  claim 1 , and an additive solution comprising a water-soluble polymer and a water. 
 
     
     
       7. The method of producing a cerium oxide polishing slurry according to  claim 6 , wherein the cerium oxide polishing slurry is a one-pack storage type. 
     
     
       8. The method of producing a cerium oxide polishing slurry according to  claim 6 , wherein the cerium oxide polishing slurry is a two-pack storage type,
 wherein one pack contains the cerium oxide slurry and another pack contains the additive solution. 
 
     
     
       9. A method of producing a cerium oxide slurry comprising
 oxidizing a cerium compound to obtain a cerium oxide, 
 crushing the cerium oxide to obtain a cerium oxide particles, 
 mixing the cerium oxide particles, a dispersant and water, and dispersing the cerium oxide particles in the water to obtain a cerium oxide disperse solution, 
 microparticulating the cerium oxide particles by collision of the cerium oxide particles in the cerium oxide disperse solution mutually at high pressure, 
 adjusting the microparticulated cerium oxide disperse solution to prepare the cerium oxide slurry, 
 measuring a ratio of weight of cerium oxide/weight of dispersant in the cerium oxide slurry, and 
 adjusting the concentration of the dispersant in the cerium oxide slurry in order to obtain a ratio that settles in a range of 20 to 40, 
 wherein mean size of particle of the cerium oxide particles in the cerium oxide slurry is 1 to 200 nm, 
 wherein the weight of cerium oxide is the weight of the cerium oxide in the cerium oxide slurry, and 
 wherein the weight of dispersant is the weight of the dispersant in the cerium oxide slurry obtained by measuring a concentration of the dispersant in the cerium oxide slurry after the cerium oxide particles are removed. 
 
     
     
       10. The method of producing a cerium oxide slurry according to  claim 9 , wherein the cerium compound is selected from the group consisting of carbonate, nitrate, sulfate or oxalate of cerium. 
     
     
       11. The method of producing a cerium oxide slurry according to  claim 9 , wherein the dispersant is a compound possessing a solubility in water of 0.1 wt. % to 99.9 wt. %. 
     
     
       12. The method of producing a cerium oxide slurry according to  claim 9 , wherein the dispersant is a salt of poly (meth)acrylic acid. 
     
     
       13. The method of producing a cerium oxide slurry according to  claim 9 , wherein the dispersant is ammonium salt polyacrylate or ammonium salt of copolymer of acrylic acid and methacrylic acid. 
     
     
       14. A method of producing a cerium oxide polishing slurry comprising
 mixing the cerium oxide slurry produced by the method according to  claim 9 , and an additive solution comprising a water-soluble polymer and a water. 
 
     
     
       15. The method of producing a cerium oxide polishing slurry according to  claim 14 , wherein the cerium oxide polishing slurry is a one-pack storage type. 
     
     
       16. The method of producing a cerium oxide polishing slurry according to  claim 14 , wherein the cerium oxide polishing slurry is a two-pack storage type,
 wherein one pack contains the cerium oxide slurry and another pack contains the additive solution.